Sunday, June 10, 2012

Corn smut: a delicious parasitic fungus

Last night, I went to Delfina for dinner. I saw corn soup with "tarturco crema" on the menu, and because of a mild obsession with corn (I LOVE CORN), had to ask our waiter what tarturco* was. He explained that it was a type of "mushroom" that grew on corn, that it was also called a Mexican Truffle...

He went for a little while more, but I had already decided we had to get it. I recognized what he was talking about as corn smut, known in Mexico as huitlacoche.  "Mexican Truffle" is just a term that people came up with to try and make the product more marketable – because in reality, it's a plant tumor.

This used to be a normal ear of corn. Source

Smuts are pathogenic fungus that replaces the fruits (ovaries) in a plant, interfering with its ability to reproduce, and causes the plant to grow galls (tumors).  In corn, the normal kernels become abnormally enlarged with fungal threads and spores.

I'd previously seen a picture of corn smut looking like the one above, so imagine my surprised when my soup came out looking like this:


"Corn soup | tarturco crema"

The corn smut had come a very long way from its tumoristic origins.  It was now an elegant shiruken-shaped dollop on top of a puréed soup. The taste was both familiar and unfamiliar, of corn and mushrooms, sweet and vanilla-y and earthy all at the same time.

I was surprised mainly because I thought there were going to be giant abnormally-shaped kernel-tumors in my soup (yes, kinda disappointed, not going to lie) but also because it was so black.

The latter shouldn't have surprised me, because apparently the blueish colors of the corn smut turn black when heat is applied.  Heat, in the form of a slow simmer, also removes the starch of the corn and turns it into the black oily paste that you see above, in the soup, and below, in the quesadilla.

Inside a huitlacoche quesadilla. Source

And even if it hadn't been cooked, the smut would've ultimately turned black anyway. When the corn is newly-infected, it becomes tinged yellow-green.  After two to three weeks, the galls are still immature, but that's when they're harvested. They're still a bit moist, which is good for cooking.

If you don't harvest the corn then, the galls start turning dry and black as they fill with the blue-black spores.  They'll make the corn look somewhat scorched and moldy, which is fitting, because the Latin name for the smut genus, Ustilago, comes for the Latin word ustilare (to burn).

After the galls have fully matured, they burst, releasing the black spores. Which then in turn attempt to infect more plants nearby, thereby continuing their cycle.

Infected corn with galls that have burst and released spores. Source

Huitlacoche is a delicacy in Mexico (as its consumption originated from ancient Aztec cuisine), and four to five hundred tons are sold annually there.  The fungus is sold at a significantly higher price than corn.  In the US though, growing the product domestically hasn't really taken off, since farmers still associate it as being a blight, and marketing "smut" or "parasitic corn fungus" to consumers has its challenges.

Fresh huitlacoche at a market in Mexico City. Source


* I tried to google the word "tarturco" but literally no results showed up.  Apparently, according to the owner of Delfina, it's just a made-up Italian word.

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